In general, requesting alternate routes is buggy and does not work reliably when you have a Stop Point in place. Most often, after an alternate route is selected, the pink line disappears even though the stop point still appears to be active. However, bringing up the route info shows the default "1min .1mi" display which never changes, and Waze is actually, at this time, routing to your final destination and not the stop point.

- IMG_2069.PNG (61.48 KiB) Viewed 603 times
The only way around this is to cancel the stop point, do your alternate route selection again, then add the stop point again. Very inefficient.
It is still unclear, when you do an alternate routes request when a stop point is active, which portion of the route is supposed to be affected: from start to stop point, or stop point to destination?